To pull a girl's sweet smelling, worn panties over one's head and wearing them around like a gas mask. To Gas Mask correctly, one must pull the panties over the head, exposing one's eyes through the leg holes and allowing the fragrant gusset to rest over the nose the mouth. Gas Masking may be performed by a male or female and may be preferred after certain activities such as running, working out, gardening and other activities that work up an irresistible, tangy smelling, zest.

Stan: Dude! WTF are you wearing on your face? Is that a pair of panties?

Frank: Yea Brrrraaaaaaahhhh!! Muh girl just ran a 5k this morning and I couldn't help but grab them when she got into the shower and do a little Gas Masking. It's irresistible. What a tangy funk she got.
Stan: Sounds zesty Broooohhhhh! Let me mask up when you are done.